Commitments And Contingencies (Narrative) (Details) (USD $)
In Millions, unless otherwise specified
 3 Months Ended 12 Months Ended 1 Months Ended
Sep. 30, 2013
Mar. 31, 2015
Mar. 31, 2014
Mar. 31, 2013
Jul. 31, 2011
Loss Contingencies [Line Items]          
Unrecorded Unconditional Purchase Obligation   $ 2,165      
Other Accrued Liabilities, Current   298 328    
Operating Leases, Future Minimum Payments Due, Future Minimum Sublease Rentals   3      
Amount of potential cash payments that could result from unrecognized tax benefits   68      
Operating Leases, Rent Expense   97 97 94  
Litigation Settlement, Amount 30        
Convertible Debt          
Loss Contingencies [Line Items]          
Long-term Debt, Gross   633 633    
Debt Instrument, Maturity Date         Jul. 15, 2016
Convertible Notes Interest [Member]          
Loss Contingencies [Line Items]          
Unrecorded Unconditional Purchase Obligation   7 [1]      
Other Accrued Liabilities, Current   $ 1      
[1] (a)Included in the $7 million coupon interest on the Notes is $1 million of accrued interest recognized as of March 31, 2015. We will be obligated to pay the $632.5 million principal amount of the Notes in cash and any excess conversion value in shares of our common stock upon redemption of the Notes at maturity on July 15, 2016, or upon earlier conversion. During the fiscal quarter ended March 31, 2015, the Sales Price Condition was met and as a result, the Notes are currently convertible at the option of the holder though July 4, 2015. See Note 12 for additional information regarding our Notes.